The present invention relates in general to semiconductor devices and, more particularly, to high current semiconductor devices for limiting current surges on a power supply bus.
Many electronics systems are designed to allow users to insert and remove circuit cards without powering down the entire system, commonly referred to as “hot swapping”. In a system where power is distributed to multiple cards on a power bus, each circuit card typically includes large filter capacitors to reduce noise on the bus, so a hot swap can produce an inrush current spike that, if not otherwise limited, reaches hundreds of amperes and which can damage the circuit card, its connector, or other circuit cards that are plugged into the system. The inrush current spikes can also produce a data loss or other system malfunction on the card being hot swapped or on other system cards. To control the deleterious effects of inrush current, hot swappable cards are configured with inrush current limiting circuits that typically include power MOSFET switches for routing load currents from the supply bus.
Circuit cards that operate at distinct current levels use unique designs and different components to implement their inrush current limiting functions. The unique designs increase the manufacturing cost of the circuit cards and the need to inventory different components makes it difficult for manufacturers of the cards and components to benefit from large economies of scale.
Hence, there is a need for an inrush current limiter that can support cards running at different current levels in order to reduce the manufacturing cost by achieving economies of scale.